Photon energy loss to interfacial charge recombination is one of the key challenges to achieving high efficiencies for solar water splitting in photoelectrochemical cells (PECs). Herein, BiVO₄-based photoanodes are constructed, where BiVO₄, cadmium sulfide nanosheets (CdS NSs), hole transport molecules (HTs), and oxygen evolution cocatalysts (OECs) assemble sequentially in a cascade band alignment for efficient photogenerated hole extraction and accumulation to OECs. In the photoanode assemblies, CdS NSs act as energetic barriers to suppress surface recombination. Thiolate-functionalized aryl amine HTs that anchor to CdS NSs are interfacial-charge-transfer mediators that efficiently extract the photogenerated holes. The oxidized HT (HT⁺) hops isoenergetically among adjacent HTs and finally accumulates oxidative equivalents to OEC. Transient absorption spectroscopy along with intensity-modulated photocurrent spectroscopy proves that HTs and CdS NSs accelerate hole-transfer kinetics and suppress recombination of surface-accumulated holes and electrons. Among the three HTs, triphenylamine shows the best performance. The best-performing photoanode assembly exhibits increased photocurrent density from 0.87 to 5.2 mA/cm². The molecular approach to hole extraction from BiVO₄ photoanodes provides a promising avenue for efficient photogenerated charge separation and collection to optimize the performance of PEC for water splitting.

中文翻译：

---

基于级联能带排列的快速空穴提取提高光电化学水氧化效率

界面电荷复合的光子能量损失是在光电化学电池 (PEC) 中实现太阳能水分解的高效率的关键挑战之一。在此，构建了基于BiVO ₄的光阳极，其中BiVO ₄、硫化镉纳米片（CdS NSs）、空穴传输分子（HTs）和析氧助催化剂（OECs）以级联带排列顺序组装，以实现高效的光生空穴提取和积累对 OEC。在光阳极组件中，CdS NSs 作为能量屏障来抑制表面复合。锚定在 CdS NS 上的硫醇盐官能化芳胺 HT 是界面电荷转移介质，可有效提取光生空穴。氧化的 HT (HT ⁺) 在相邻的 HT 之间等能跳跃并最终积累 OEC 的氧化等效物。瞬态吸收光谱和强度调制光电流光谱证明 HTs 和 CdS NSs 加速了空穴转移动力学并抑制了表面积累的空穴和电子的复合。在三种 HT 中，三苯胺表现出最好的性能。性能最佳的光阳极组件表现出从 0.87 增加到 5.2 mA/cm ²的光电流密度。_{从 BiVO 4}光阳极中提取空穴的分子方法为有效的光生电荷分离和收集提供了一条有希望的途径，以优化 PEC 的水分解性能。